Hermione stepped forward, raised her hand, and knocked three times with her knuckles.
Knock, knock, knock.
Dead silence behind the door.
Harry was just thinking they would be turned away when the door creaked open on its own. A pitch-black gap silently invited them inside.
Cold air hit them in the office. The mingled smells of wormwood, dragon liver, and unidentified herbs were nauseatingly pungent.
Snape sat behind his desk without looking at them, scraping a shriveled plant root with a silver knife. The blade made a rasping sound that set their teeth on edge.
Glass jars on the wall shelves held assorted preserved creatures. In the dim light, those cloudy eyes all stared fixedly at the three uninvited visitors.
"What is it?" Snape did not even look up. His voice held no warmth.
Harry steeled himself, stepped forward, and placed the commission letter on the corner of Snape's desk.
"Ahem, Professor." Harry cleared his throat. "Our Charon Detective Agency has been commissioned by the Academic Affairs Office to investigate the theft from your private storeroom."
Snape's knife stopped.
He raised his head, his eyes full of mockery.
"Potter, the Wizarding World's great Chosen One, now deigns to become a... detective?" He drew out the words, his lips twisted cruelly. "Should I feel honored?"
His gaze shifted to Ron, full of disdain. "Mr. Weasley, someone who lived with a rat for over a decade without noticing anything amiss, thinks he is fit to be a detective?"
Ron's face turned liver-red.
Snape's gaze finally settled on Hermione's face. "Miss Granger, I thought your brain could at least distinguish between a classroom game and an exercise in self-humiliation."
Hermione flushed, but kept her back straight.
"Professor, we are serious. Procedure requires us to interview the client. Please tell us exactly what you